diff --git a/makefile b/makefile
index 7443a25e01b..caa79f2ba8a 100644
--- a/makefile
+++ b/makefile
@@ -61,9 +61,11 @@ endif
 #-------------------------------------------------
 
 ifndef TARGETOS
+
 ifeq ($(OS),Windows_NT)
 TARGETOS = win32
 else
+
 ifneq ($(CROSSBUILD),1)
 UNAME = $(shell uname -a)
 
@@ -93,8 +95,23 @@ endif
 
 endif # CROSS_BUILD
 endif # Windows_NT
+
 endif # TARGET_OS
 
+
+ifeq ($(TARGETOS),win32)
+
+# Autodetect PTR64
+ifndef PTR64
+ifneq (,$(findstring mingw64-w64,$(PATH)))
+PTR64=1
+endif
+endif
+
+endif
+
+
+
 #-------------------------------------------------
 # configure name of final executable
 #-------------------------------------------------
diff --git a/src/osd/windows/windows.mak b/src/osd/windows/windows.mak
index 10c7e8f743a..21d6efeb9a3 100644
--- a/src/osd/windows/windows.mak
+++ b/src/osd/windows/windows.mak
@@ -78,18 +78,6 @@ OBJDIRS += $(WINOBJ)
 
 
 
-#-------------------------------------------------
-# auto-detect PTR64
-#-------------------------------------------------
-
-ifndef PTR64
-ifneq (,$(findstring mingw64-w64,$(PATH)))
-PTR64=1
-endif
-endif
-
-
-
 #-------------------------------------------------
 # configure the resource compiler
 #-------------------------------------------------